Quantum Differences between Heavy and Light Water.

The structures of heavy and light water at ambient conditions are investigated with the combined techniques of x-ray diffraction, neutron diffraction, and computer simulation. It is found that heavy water is a more structured liquid than light water. We find the OH bond length in H2O is approximately 3% longer than the OD bond length in D2O. This is a much larger change than current predictions. Corresponding to this, the hydrogen bond in light water is approximately 4% shorter than in heavy water, while the intermolecular HH distance is approximately 2% longer.